1. Field of Invention
This invention relates generally to furnaces and more particularly to furnaces driven by power plants in the form of internal combustion engines.
2. Discussion of the Prior Art
It is generally recognized in the furnace industry that most present day furnaces for heating building structures are much less efficient than desired and that a great deal of the heat energy produced by combustion type furnaces escapes unused up through the conventional vents, flues or chimneys. In addition, it is also recognized that those furnaces that do not rely upon combustion as an energy source (such as electric furnaces) are more expensive to operate under present day circumstances than those furnaces which utilize fluid or liquid fuels for combustion. It has thus become desirable to utilize gas or liquid fuel operated furnaces which are more efficient.
With regard to fuel combustion type furnaces, it further appears that those furnaces which heat a liquid for circulation such as water, are generally considered more efficient than those which do not heat a liquid for the heat transfer medium, such as direct forced air heating furnaces.
The conventional hot water furnace normally uses a combustion flame using natural gas, fuel oil or gasoline as the fuel to heat metal coils containing the water or liquid which is then circulated throughout the building for heat distribution. In this situation, it is obvious that the combustion fumes will eventually be vented to the atmosphere and that in doing so, much of the heat which might otherwise be utilized to heat the coils escapes through the chimney or exhaust system.
It has also been recognized that internal combustion engines which use a gas or liquid fuel may be utilized to heat liquids. However, these furnace or heating systems have been considered to be even less efficient than the conventional direct combustion liquid heaters or furnaces, as evidenced by the widely accepted use of the latter.
For example, U.S. Pat. No. 937,879 issued to E. B. Smith on Oct. 26, 1909, discloses utilization of the exhaust heat from an internal combustion engine to in turn heat a liquid for circulation throughout a building structure to dissipate the heat therein. The structure of Smith, however, makes utilization only of the exhaust heat, and it is obvious that a great deal of additional energy given off by the internal combustion engine is wasted, such as the heat created by the friction of the engine parts and the mechanical energy otherwise created by the engine. Improvements in recovering more of this useful energy have been made over the years.
For example, U.S. Pat. No. 2,256,303 issued to R. D. Williams on Sept. 16, 1941, discloses a heating system utilizing an internal combustion engine where air is flowed over the entire body of the engine in order to capture some of the heat dissipated from the engine body, and the mechanical energy given off from the engine is also further utilized to pump the heated air through the heating system.
U.S. Pat. No. 2,748,570 issued to J. H. Booth on June 5, 1956 also discloses the use of a combustion engine driven heater for heating liquids, wherein the heat of the internal combustion engine coolant is not only captured, but in addition he also attempts to capture as much of the heat as possible which is given off from the engine body or housing by using the hot air surrounding the engine body. However, this structure does not make full utilization of the mechanical energy given off from the engine for heating the fluid.
Other inventors have taken a different approach to heating liquids by the use of friction heaters. For example, see U.S. Pat. No. 1,819,057 issued to G. F. Archer on Aug. 18, 1931 and U.S. Pat. No. 1,919,681 issued to J. W. Anderson on July 25, 1933. Both of these liquid heaters utilize mechanical friction devices to heat a surrounding liquid. However, here again full efficiency of both apparatus are not realized, as considerable energy is required to move these frictional parts relative to each other and the heat given off by this prime mover is not captured for further utilization in heating the liquid.
It is the principal object of the present invention to eliminate or at least minimize the foregoing disadvantages of the prior art liquid heating devices and to provide a liquid heater which is more efficient and economical in operation.
It is a further object of the present invention to provide a liquid heater which does not require use of valuable space within a building structure as is required by most conventional heaters of present day use.